Human activity has altered >70% of land surface

The Big Picture: Earth’s systems and humans interact


  • Biodiversity can be measured at many scales
    • maintaining high biodiversity has huge benefits


  • Conservation biology focuses on the population level
    • small populations have genetic problems


  • Global Change is occurring at unprecedented rates
    • Yes, change has occurred over Earth’s history
    • No, it has never occurred this quickly


  • Are we in a new mass extinction?

What is Biodiversity?


  • Level 1: Genetic Diversity
    • within and among populations
    • loss of alleles reduces adaptive potential


  • Level 2: Species Diversity
    • number of species in a system
    • local or whole extinctions possible


  • Level 3: Ecosystem Diversity
    • variety of ecosystems on Earth
    • provide services to humans

How do we measure biodiversity?


  • Genetic Diversity: alleles in populations
    • what happens when a population disappears?


  • Species Diversity
    • how many species?
    • how even are the species?
    • roles of dominant, keystone & rare species
    • are endemic species present?


  • Ecosystem Diversity
    • what benefits do healthy ecosystems provide?
    • are the abiotic variables changing?

The Selfish View: What does biodiversity provide us?


  • Moral code: Each species belongs
    • what is the role of humans in causing, saving, or allowing extinction?


  • Practical benefits for all 3 biodiversity types
    • genetic diversity a tool for medicines
    • diversity feeds, clothes and houses humans


  • Ecosystem Services to humans
    • raw goods
    • health and well being
    • regulation of air, water, etc

Why is biodiversity changing?


  • Human activities threaten biodiversity
    • at each scale


  • Threats posed by humans fall into 4 categories
  1. habitat loss
  2. species introductions
  3. over-harvesting
  4. global change


  • Landscape change by humans is huge threat
    • nearly all land surface has been altered
    • causes fragmentation or loss of habitat

Introduced species and over-harvesting

Native vs Non-Native vs Invasive Species

How does conservation biology work?



  • Small populations are the most vulnerable
    • population getting pushed to extinction


  • Small populations vulnerable to inbreeding
    • genetic issues of non-random mating


  • Small populations vulnerable to genetic drift
    • chance loss of alleles


  • Goal: Maintain genetic diversity to avoid extinction vortex

How does conservation biology work?


  • Detect downward trends in population sizes
    • may be a large population


  • Prioritize the factors causing decline
    • habitat loss, climate change, etc.


  • What are the environmental needs of the species?
    • What is the root cause of the decline?
    • How do we stop it?

Landscape conservation: Building habitat corridors

Establishing large scale protected areas (terrestrial or aquatic) is first priority

Global Change: What is in a name?



  • Global warming:


  • Climate change:
    • more than just temperature
    • mostly related to post 1950’s


  • Global change:
    • e.g. nutrient cycles, biodiversity, land use, sea level rise, ice loss

Global Change: Climate change


  • Climate change is strongly related to the chemistry of the atmosphere
    • enhances existing greenhouse gas effect
    • CO2, CH4, NOx & H2O


  • Greenhouse gases intercept and absorb radiation
    • more greenhouse gases = higher temperatures


  • Burning of fossil fuels increases atmospheric CO2
    • makes biosphere warmer
    • impacts weather and climate

Greenhouse effect is a natural process!

Global Change: What can we do?


  • We cannot save all habitats
    • which patches are most crucial?


  • Sustainable development
    • better engineer man-made ecosystems
    • food security while reducing environmental impacts of agriculture
    • food security while maintaining ecosystem services


  • Curb global emissions
    • projected warming by end of century is uncertain
    • changes needed at individual, community and policy levels

Future of the Biosphere: New Mass Extinction?

Present-day extinction rate is 1,000 to 10,000 times the background extinction rate because of deforestation, habitat loss, overhunting, pollution, climate change, and other human activities